Usually they are mediocre chefs. Actually I don't believe that a chef who doesn't like what he's cooking can make it right, and almost every awesome chef I know demand more from the quality of their dishes than their customers.
The product of a chef is the cooking, not the cooked product itself.
I often buy better ingredients than what's found at any restaurant, but I pay to sit at one because they're prepared, cooked and taste better when done by a professional.
